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Android studio java can't get context in Fragment

I am absolute beginner for this, I'm sorry if this such a dumb mistakes.
so, I created fragment in which i have got recyclerView, but my recycler view is empty, i saw that my context is empty, and i think, that it can be the reason of this, i try to use getActivity
here is code of my fragment
package com.example.pocketcinema;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.QueryDocumentSnapshot;
import com.google.firebase.firestore.QuerySnapshot;
import java.util.ArrayList;
import java.util.List;
public class SearchFragment extends Fragment implements RecyclerViewInterface {
private RecyclerView recyclerView;
RecyclerViewInterface rci;
MyAdapter myAdapter;
public List<String> nameOfFilm, youTubeUrl, photoUrl, descriptionToFilm, category;
FirebaseFirestore db = FirebaseFirestore.getInstance();
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
recyclerView = inflater.inflate(R.layout.fragment_search, container,
false).findViewById(R.id.filmsList);
rci = this;
nameOfFilm = new ArrayList<>();
youTubeUrl = new ArrayList<>();
photoUrl = new ArrayList<>();
descriptionToFilm = new ArrayList<>();
category = new ArrayList<>();
loadFilmsFromDB();
return inflater.inflate(R.layout.fragment_search, container, false);
}
private void loadFilmsFromDB() {
Context context = requireContext();
db.collection("films").get().addOnCompleteListener(new
OnCompleteListener<QuerySnapshot>()
{
#Override
public void onComplete(#NonNull Task<QuerySnapshot> task) {
for (QueryDocumentSnapshot document : task.getResult()) {
nameOfFilm.add(document.get("nameOfFilm").toString());
descriptionToFilm.add(document.get("descriptionToFilm").toString());
photoUrl.add(document.get("imageUrl").toString());
youTubeUrl.add(document.get("videoURL").toString());
category.add(document.get("category").toString());
myAdapter = new MyAdapter(context, nameOfFilm, descriptionToFilm,
photoUrl, youTubeUrl,
rci, category);
recyclerView.setAdapter(myAdapter);
recyclerView.setLayoutManager(new LinearLayoutManager(context));
}
}
});
}
here is screenshot with debuger, you can see that context = null
context = null
here you can see that i set layout for recyclerView
with logcat
here is Adapter
package com.example.pocketcinema;
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.cardview.widget.CardView;
import androidx.recyclerview.widget.RecyclerView;
import com.squareup.picasso.Picasso;
import java.util.List;
public class MyAdapter extends
RecyclerView.Adapter<MyAdapter.MyViewHolder> {
Context ct;
List<String> name, description, image, video, category;
private final RecyclerViewInterface recyclerViewInterface;
public MyAdapter(Context ct, List<String> nameOfFilm, List<String>
descriptionOfFilm, List<String> imageUrl, List<String> videoUrl,
RecyclerViewInterface rci,List<String> category) {
name = nameOfFilm;
description = descriptionOfFilm;
image = imageUrl;
video = videoUrl;
this.ct = ct;
recyclerViewInterface = rci;
this.category = category;
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int
viewType) {
LayoutInflater inflater = LayoutInflater.from(ct);
View view = inflater.inflate(R.layout.my_row, parent, false);
return new MyViewHolder(view, recyclerViewInterface);
}
#Override
public void onBindViewHolder(#NonNull MyViewHolder holder, int
position) {
holder.nameFilm.setText(name.get(position));
holder.cardView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(ct, PlayerActivity.class);
}
});
Picasso.get().load(image.get(position)).into(holder.image2);
}
#Override
public int getItemCount() {
return image.size();
}
public static class MyViewHolder extends RecyclerView.ViewHolder {
TextView nameFilm;
ImageView image2;
CardView cardView;
public MyViewHolder(#NonNull View itemView, RecyclerViewInterface
recyclerViewInterface) {
super(itemView);
nameFilm = itemView.findViewById(R.id.nameTV);
image2 = itemView.findViewById(R.id.imageView2);
cardView = itemView.findViewById(R.id.cardView);
itemView.findViewById(R.id.sectionOFRecyclerView).setOnClickListener
(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (recyclerViewInterface != null) {
int pos = getAdapterPosition();
if (pos != RecyclerView.NO_POSITION) {
recyclerViewInterface.onItemClick(pos);
}
}
}
});
}
}
}
myAdapter isn't null

You are trying to create an instance of activity as global variable. That means the context has not been generated yet.
Basically you can just use requireContext() method of Fragment class. This will provide you the context.
As I have mentioned in comment, you need to update your onCreateView method as below:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_search, container, false);
}
Then, you need to initialize your view and other stuff on onViewCreated method. You can update that method like this:
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
recyclerView = view.findViewById(R.id.filmsList);
textView = view.findViewById(R.id.test);
rci = this;
nameOfFilm = new ArrayList<>();
youTubeUrl = new ArrayList<>();
photoUrl = new ArrayList<>();
descriptionToFilm = new ArrayList<>();
category = new ArrayList<>();
loadFilmsFromDB();
}
Notes
You don't have to send many string parameters to your adapter. It is better to create a Model class for that item, and send the list of that item. So, model classes will have all the data you need, and you can use them from that model. This will give you better coding style and will let you manage your data easier.
To communicate with your XML layout, you can use ViewBinding or DataBinding for that. This will also help you to use your view elements without creating variables for each of them.

SharedPreferences Data spreads on every Fragment

I got a problem with the date of my SharedPreferences. I am using 5 Fragment wher you can dynamically add item to a RecyclerView. The Problem is that when ever I save my data on a particular fragment and reload the app the value that has been saved loads into every single Fragment of mine.It actually save the data to the Fragment it is on.I am using Gson to save my ArrayList of items
This is my Fragment (Fragment0 from 5 in total, the others are just copied and refactored)
package com.example.barryblack;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.ItemTouchHelper;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import java.lang.reflect.Type;
import java.util.ArrayList;
import static android.content.Context.MODE_PRIVATE;
public class FragmentPage0 extends Fragment {
private ExampleAdapter mAdapter;
private EditText editTask;
ArrayList<MyItem> items;
private Button insertbtn;
private Button stateButton;
private TextView taskText;
private String task;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable
Bundle savedInstanceState) {
CreateExampleList();
View view = inflater.inflate(R.layout.page_fragment0, container, false);
loadData();
RecyclerView recyclerView = view.findViewById(R.id.listRecyclerView);
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getActivity());
new ItemTouchHelper(itemTouchHelperCallback).attachToRecyclerView(recyclerView);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemViewCacheSize(500);
mAdapter = new ExampleAdapter(items);
recyclerView.setAdapter(mAdapter);
taskText = view.findViewById(R.id.tv_country);
insertbtn = view.findViewById(R.id.button_insert);
editTask = view.findViewById(R.id.editTask);
stateButton = view.findViewById(R.id.tv_button);
insertbtn.setEnabled(false);
editTask.addTextChangedListener(new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
String taskInput = editTask.getText().toString().trim();
insertbtn.setEnabled(!taskInput.isEmpty());
}
#Override
public void afterTextChanged(Editable s) {
task = editTask.getText().toString().trim();
}
});
insertbtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
InsertItem();
SaveData();
editTask.setText(null);
}
});
return view;
}
private void SaveData() {
SharedPreferences sharedPreferences = this.getActivity().getSharedPreferences("shared
preferences", MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
Gson gson = new Gson();
String json = gson.toJson(items);
editor.putString("task list", json);
editor.apply();
}
private void loadData() {
SharedPreferences sharedPreferences = this.getActivity().getSharedPreferences("shared
preferences", MODE_PRIVATE);
Gson gson = new Gson();
String json = sharedPreferences.getString("task list", null);
Type type = new TypeToken<ArrayList<MyItem>>() {
}.getType();
items = gson.fromJson(json, type);
if (items == null) {
items = new ArrayList();
}
}
public void InsertItem() {
items.add(new MyItem(task, stateButton));
mAdapter.notifyItemInserted(items.size());
}
private void CreateExampleList() {
items = new ArrayList<MyItem>();
}
ItemTouchHelper.SimpleCallback itemTouchHelperCallback = new ItemTouchHelper.SimpleCallback(0,
ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
#Override
public boolean onMove(#NonNull RecyclerView recyclerView, #NonNull RecyclerView.ViewHolder
viewHolder, #NonNull RecyclerView.ViewHolder target) {
return false;
}
#Override
public void onSwiped(#NonNull RecyclerView.ViewHolder viewHolder, int direction) {
items.remove(viewHolder.getAdapterPosition());
mAdapter.notifyItemRemoved(viewHolder.getAdapterPosition());
SaveData();
}
};
}
This is my Adapter. I think the problem is inside the OnCreateViewHolder but im not quiet sure
package com.example.barryblack;
import android.content.Context;
import android.content.SharedPreferences;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
public class ExampleAdapter extends RecyclerView.Adapter<ExampleAdapter.ExampleViewHolder> {
private ArrayList<MyItem> mExampleList;
public static class ExampleViewHolder extends RecyclerView.ViewHolder {
public TextView mTextView;
private EditText topicName;
public Button mButton;
private int clicks = 1;
public static final String SHARED_PREFS = "sharedPrefs";
public static final String TOPIC = "topic";
public static final String CLICKS = "clicks";
public ExampleViewHolder(View itemView) {
super(itemView);
mTextView = itemView.findViewById(R.id.tv_country);
mButton = itemView.findViewById(R.id.tv_button);
topicName = itemView.findViewById(R.id.editText);
mButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
clicks++;
if (clicks % 2 == 0) {
mButton.setBackgroundResource(R.drawable.button_green);
}else
mButton.setBackgroundResource(R.drawable.button_red);
}
});
}
}
public ExampleAdapter(ArrayList<MyItem> exampleList) {
mExampleList = exampleList;
}
#Override
public ExampleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.example_item, parent, false);
ExampleViewHolder evh = new ExampleViewHolder(v);
return evh;
}
#Override
public void onBindViewHolder(ExampleViewHolder holder, int position) {
MyItem currentItem = mExampleList.get(position);
holder.mTextView.setText(currentItem.getTaskText());
}
#Override
public int getItemCount() {
return mExampleList.size();
}
}

Use this for your fragments. So every fragment has his own SharedPreferences
private static final String SHARED_PREFS_FRAGMENT_A = "fragmentA";
private static final String SHARED_PREFS_FRAGMENT_B = "fragmentB";
...
SharedPreferences sharedPreferences = getActivity().getSharedPreferences(SHARED_PREFS_FRAGMENT_A , MODE_PRIVATE);

When I move from fragment b to fragment A after adding my new listitem, my new listitem is not showing in recyclerview

I am making note taking app.i have two fragments in my app first fragment A (ListFragment) contains the recycler adapter .
while when I press adding floating button first fragment A (ListFragment) is replaced with next fragment B(AddingFragment) in which I type new data and then again press adding floating button on fragment B(AddingFragment) to add that new data in data set and then press backfloating button on my fragment B to move back to Fragment A(with recycler adapter) .
This new data item is added to data list every time but never becomes visible in recycler adapter in Fragment A.
package com.example.anonymous.note_taking_app;
import android.app.ActionBar;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.app.Fragment;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
public class AddingFragment extends Fragment {
public AddingFragment()
{
}
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.fragment_adding, container, false);
return view;
}
#Override
public void onResume()
{
super.onResume();
FloatingActionButton floating = (FloatingActionButton) getActivity().findViewById(R.id.addingfloatingbutton);
floating.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
Log.i("floating_button", "floating button 2 clicked");
EditText title = (EditText) getActivity().findViewById(R.id.firsttextview);
EditText detial = (EditText) getActivity().findViewById(R.id.secondtextview);
DatabaseHelper db = new DatabaseHelper(getActivity().getApplication());
boolean insert = db.insert(title.getText()+"",detial.getText()+"");
if(insert==true)
{
com.example.anonymous.note_taking_app.ListAdapter l = new com.example.anonymous.note_taking_app.ListAdapter();
ListFragment.it.add(new ListItem(title.getText()+"",detial.getText()+""));
l.notifyItemInserted(ListFragment.it.size()-1);//DataSetChanged();
l.notifyDataSetChanged();
for(int i=0;i<ListFragment.it.size();i++)
{
Log.i("List item"+i+"", ListFragment.it.get(i).getNoteTitle());
}
Log.i("insertion", "is added");
}
else
{
Log.i("insertion", "is not added");
}
}
});
FloatingActionButton floatings = (FloatingActionButton) getActivity().findViewById(R.id.addcancelfloatingbutton);
floatings.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view)
{
final FragmentManager fragmentManager = getFragmentManager();
fragmentManager.popBackStackImmediate();
}
});
}
}
//
package com.example.anonymous.note_taking_app;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;
import android.widget.Toast;
import android.app.Fragment;
import java.util.ArrayList;
/**
* Created by Anonymous on 12/13/2017.
*/
public class ListAdapter extends RecyclerView.Adapter<ListAdapter.holderclas> implements EditDilogue.EditDilougeinterface
{
static ArrayList<ListItem> i;
Context context;
View view;
ImageButton share;
ImageButton edit;
static int lastposition;
android.app.FragmentManager fm;
public ListAdapter(ArrayList<ListItem> i,android.app.FragmentManager fm)
{
this.i=i;
this.fm=fm;
}
public ListAdapter()
{
}
#Override
public ListAdapter.holderclas onCreateViewHolder(ViewGroup parent, int viewType)
{
view= LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item,parent,false);
holderclas h = new holderclas(view);
share = (ImageButton) view.findViewById(R.id.share);
edit = (ImageButton) view.findViewById(R.id.edit);
return h;
}
#Override
public void onBindViewHolder(ListAdapter.holderclas holder, final int position)
{
final int y= position;
lastposition = position;
final ListItem it = i.get(position);
holder.title.setText(it.getNoteTitle());
holder.details.setText(it.getNoteDetail());
ImageButton b =(ImageButton) view.findViewById(R.id.delete);
b.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
Log.i("size", i.size()+"");
i.remove(y);
notifyDataSetChanged();
}
});
share.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
Log.i("share", "share");
}
});
edit.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
Log.i("edit", i.size()+"edit");
EditDilogue ed = new EditDilogue();
Bundle args = new Bundle();
args.putString("title", it.getNoteTitle());
args.putString("detail", it.getNoteDetail());
ed.setArguments(args);
ed.setTargetFragment(new ListFragment(),1);
ed.show(fm,"fragment");
}
});
}
#Override
public int getItemCount()
{
return i.size();
}
#Override
public void deleteandadd(String titlestring, String detailstring)
{
String oldtitle = i.get(lastposition).getNoteTitle();
String olddetail = i.get(lastposition).getNoteDetail();
Log.i("string", titlestring);
Log.i("string", detailstring);
}
public class holderclas extends RecyclerView.ViewHolder
{
TextView title;
TextView details;
public holderclas(View itemView)
{
super(itemView);
title=(TextView) itemView.findViewById(R.id.title);
details=(TextView) itemView.findViewById(R.id.detail);
}
}
}
//
package com.example.anonymous.note_taking_app;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ListAdapter;
import java.util.ArrayList;
/**
* Created by Anonymous on 12/13/2017.
*/
public class ListFragment extends Fragment implements EditDilogue.EditDilougeinterface
{
RecyclerView recyClerView;
RecyclerView.Adapter adapter;
RecyclerView.LayoutManager layoutManager;
public static ArrayList<ListItem> it;
public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState)
{
it = new ArrayList<>();
View view = inflater.inflate(R.layout.fragment_list, parent, false);
FloatingActionButton floating = (FloatingActionButton) view.findViewById(R.id.listfloatingbutton);
floating.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view)
{
Fragment frg = new AddingFragment();
FragmentManager manager = getFragmentManager();
FragmentTransaction trans = manager.beginTransaction();
trans.replace(R.id.placeholder,frg);
trans.addToBackStack("addingfragment");
trans.commit();
AddingFragment()).addToBackStack("addingfragment").commit();
}
});
for(int i=0;i<5;i++)
{
ListItem t = new ListItem("Time Bank",
"Bank should contain atleast $2000 rupees then i will leave this matter") ;
it.add(t);
}
recyClerView=(RecyclerView) view.findViewById(R.id.recycle);
FragmentManager fm = getFragmentManager();
com.example.anonymous.note_taking_app.ListAdapter l = new com.example.anonymous.note_taking_app.ListAdapter(it,fm);
recyClerView.setAdapter(l);
layoutManager = new LinearLayoutManager(getActivity());
recyClerView.setLayoutManager(layoutManager);
return view;
}
#Override
public void onResume()
{
super.onResume();
if(adapter!=null)
{
adapter.notifyDataSetChanged();
adapter.notifyItemInserted(ListFragment.it.size()-1);
}
}
#Override
public void deleteandadd(String titlestring, String detailstring)
{
String oldtitle = com.example.anonymous.note_taking_app.ListAdapter.i.get(com.example.anonymous.note_taking_app.ListAdapter.lastposition).getNoteTitle();
String olddetail = com.example.anonymous.note_taking_app.ListAdapter.i.get(com.example.anonymous.note_taking_app.ListAdapter.lastposition).getNoteDetail();
Log.i("string", titlestring);
Log.i("string", detailstring);
}
}

Retrofit RecyclerView not working in tab layout

I've been trying to implement a recycler view inside a fragment which displays parsed data using the retrofit library. Whenever I run the project the lists don't show and the monitor says "E/RecyclerView: No adapter attached; skipping layout". Here is my code:
MainActivity:
package com.example.ahmed.newsapp
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.design.widget.TabLayout;
public class MainActivity extends AppCompatActivity {
private static final String TAG = MainActivity.class.getSimpleName();
private static final int ACTIVITY_NUM = 0;
// TODO - insert your themoviedb.org API KEY here
private final static String API_KEY = "<API KEY CENSORED>";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Find the view pager that will allow the user to swipe between fragments
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
// Create an adapter that knows which fragment should be shown
FragmentAdapter adapter = new FragmentAdapter(getSupportFragmentManager
());
// Set the adapter onto the view pager
viewPager.setAdapter(adapter);
TabLayout ob=(TabLayout) findViewById(R.id.sliding_tabs);
ob.setupWithViewPager(viewPager);
}
}
FragmentAdapter:
package com.example.ahmed.newsapp;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
/**
* Created by ahmed on 3/22/2017.
*/
public class FragmentAdapter extends FragmentPagerAdapter {
private String tabs[]=new String[]{"Home","Family Members","Colors"};
public FragmentAdapter(FragmentManager fm){
super(fm);
}
#Override
public Fragment getItem(int position) {
switch(position){
case 0:
return new HomeActivity();
case 1:
return new HomeActivity();
/* case 2:
return new ColorFragment();*/
}
return null;
}
#Override
public CharSequence getPageTitle(int position) {
return tabs[position];
}
#Override
public int getCount() {
return 2;
}
}
NewsAdapter:
package com.example.ahmed.newsapp;
/**
* Created by ahmed on 27-08-17.
*/
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;
import java.util.List;
public class NewsAdapter extends RecyclerView.Adapter<NewsAdapter.NewsViewHolder> {
private List<News> news;
private int rowLayout;
private Context context;
public static class NewsViewHolder extends RecyclerView.ViewHolder {
LinearLayout moviesLayout;
TextView movieTitle;
TextView data;
TextView movieDescription;
TextView rating;
public NewsViewHolder(View v) {
super(v);
moviesLayout = (LinearLayout) v.findViewById(R.id.movies_layout);
movieTitle = (TextView) v.findViewById(R.id.title);
data = (TextView) v.findViewById(R.id.subtitle);
movieDescription = (TextView) v.findViewById(R.id.description);
rating = (TextView) v.findViewById(R.id.rating);
}
}
public NewsAdapter(List<News> news, Context context) {
this.news = news;
// this.rowLayout = rowLayout;
this.context = context;
}
#Override
public NewsViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.list_item_news, parent, false);
return new NewsViewHolder(view);
}
#Override
public void onBindViewHolder(NewsViewHolder holder, final int position) {
holder.movieTitle.setText(news.get(position).getTitle());
holder.data.setText(news.get(position).getReleaseDate());
holder.movieDescription.setText(news.get(position).getOverview());
holder.rating.setText(news.get(position).getVoteAverage().toString());
}
#Override
public int getItemCount() {
return news.size();
}
}
HomeActivity:
package com.example.ahmed.newsapp;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;
import java.util.List;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import static android.content.ContentValues.TAG;
public class HomeActivity extends Fragment {
RecyclerView recyclerView;
private final static String API_KEY = "<API KEY CENSORED>";
NewsAdapter adapter;
List<News> news,dummy;
View rootview;
public HomeActivity() {
// Required empty public constructor
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootview = inflater.inflate(R.layout.activity_home, container, false);
if (API_KEY.isEmpty()) {
Toast.makeText(getContext(), "Please obtain your API KEY first from themoviedb.org", Toast.LENGTH_LONG).show();
return rootview;
}
ApiInterface apiService =
ApiClient.getClient().create(ApiInterface.class);
recyclerView = (RecyclerView) rootview.findViewById(R.id.home_page_recycler_view);
adapter= new NewsAdapter(dummy,getContext());
Call<NewsResponse> call = apiService.getTopRatedMovies(API_KEY);
call.enqueue(new Callback<NewsResponse>() {
#Override
public void onResponse(Call<NewsResponse> call, Response<NewsResponse> response) {
news = response.body().getResults();
adapter.notifyDataSetChanged();
adapter=new NewsAdapter(news,getContext());
recyclerView.setAdapter(adapter);
// adapter.setData(news);
Log.d(TAG, "Number of movies received: " + news.size());
}
#Override
public void onFailure(Call<NewsResponse> call, Throwable t) {
// Log error here since request failed
Log.e(TAG, t.toString());
}
});
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false));
return rootview;
}
}

i think the problem is in your FragmentAdapter class
just remove return null; statement from your FragmentAdapter like below code
#Override
public Fragment getItem(int position) {
Fragment fragment=null;
switch(position){
case 0:
fragment= new HomeActivity();
case 1:
fragment= new HomeActivity();
/* case 2:
return new ColorFragment();*/
}
return fragment;
}
change this
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false));
recyclerView = (RecyclerView) rootview.findViewById(R.id.home_page_recycler_view);
adapter= new NewsAdapter(dummy,getContext());

You don't need to recreate your adapter when you receive response.
It may looks like:
recyclerView = (RecyclerView) rootview.findViewById(R.id.home_page_recycler_view);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
adapter = new NewsAdapter(null, getActivity());
recyclerView.setAdapter(adapter);
Call<NewsResponse> call = apiService.getTopRatedMovies(API_KEY);
call.enqueue(new Callback<NewsResponse>() {
#Override
public void onResponse(Call<NewsResponse> call, Response<NewsResponse> response) {
news = response.body().getResults();
adapter.setData(news);
Log.d(TAG, "Number of movies received: " + news.size());
}
...
And in NewsAdapter:
...
public void setData(Collection<News> newData) {
news.clear();
news.addAll(newData);
notifyDataSetChanged();
}
#Override
public int getItemCount() {
return news == null ? 0 : news.size();
}
...

findfragmentbyid returns null in mainActivity hosting 3 fragments under a viewpager

I am trying to write different functionalities for my FloatingActionButton depending on the fragment that the mainActivity is currently hosting. Yet for for reason in my onClick() method, getSupportFragmentManager().findFragmentById() returns null.
I haven't seen any examples of this question implemented with a viewpager and I am curious if there is a different approach I have to take.
MainActivity
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.View;
public class MainActivity extends FragmentActivity {
private Adapter mAdapter;
private ViewPager mViewPager;
private static FloatingActionButton bButton;
private static String UID;
private Intent intent;
public static String getUID(){
return UID;
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAdapter = new Adapter(getSupportFragmentManager());
mViewPager = (ViewPager)findViewById(R.id.vPager);
mViewPager.setAdapter(mAdapter);
intent = getIntent();
UID = intent.getStringExtra("uid");
bButton = (FloatingActionButton)findViewById(R.id.bButton);
bButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.fragContainer);
if(fragment == null){
Log.e("TAG","FRAGMENT IS NULL!!");
}
else{
Log.e("TAG","FRAGMENT IS NOT NULL!!");
}
}
});
}
}
NewsFeedFragment
import android.os.Bundle;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.ListFragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import com.firebase.client.Firebase;
import com.firebase.client.FirebaseError;
import com.mycompany.neighbors.R;
import com.mycompany.neighbors.SinglePost;
import java.util.ArrayList;
/**
* Created by joshua on 5/25/2016.
*/
public class NewsFeedFragment extends ListFragment implements AdapterView.OnItemClickListener{
private ListView lv;
private TextView tvUserName;
private TextView tvStatus;
private ArrayList<SinglePost> posts = new ArrayList<>();
private static final String POSTS_PATH = "MY_PATH";
private Firebase postsRef;
// private static final String FRAGMENT_POST = "post";
public void postFragment(){
Log.d("TAG", "Doing something else");
PostFragment postFragment = new PostFragment();
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.fragContainer,postFragment)
.addToBackStack(null)
.commit();
}
#Override
public void onViewCreated(View v, Bundle s){
lv = getListView();
lv.setOnItemClickListener(this);
}
#Override
public void onCreate(Bundle savedInstance){
super.onCreate(savedInstance);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState){
View v = inflater.inflate(R.layout.fragment_post_feed_item,parent,false);//changed
tvUserName = (TextView)v.findViewById(R.id.tvUN);
tvStatus = (TextView)v.findViewById(R.id.tvStatus);
postsRef = new Firebase(POSTS_PATH);
postsRef.addChildEventListener(new com.firebase.client.ChildEventListener() {
#Override
public void onChildAdded(com.firebase.client.DataSnapshot dataSnapshot, String s) {
SinglePost post = dataSnapshot.getValue(SinglePost.class);
post.setKey(dataSnapshot.getKey());
posts.add(0, post);
if(posts.size() > 0) {
PostAdapter adapter = new PostAdapter(posts);
setListAdapter(adapter);
}else{
Toast toast = Toast.makeText(getActivity(),"No data", Toast.LENGTH_SHORT);
toast.show();
}
}
#Override
public void onChildChanged(com.firebase.client.DataSnapshot dataSnapshot, String s) {
}
#Override
public void onChildRemoved(com.firebase.client.DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(com.firebase.client.DataSnapshot dataSnapshot, String s) {
}
#Override
public void onCancelled(FirebaseError firebaseError) {
}
});
return v;
}
#Override
public void onListItemClick(ListView l, View v, int position, long id){
SinglePost p = ((PostAdapter) getListAdapter()).getItem(position);
}
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
}
private class PostAdapter extends ArrayAdapter<SinglePost>{
public PostAdapter(ArrayList<SinglePost> singlePost){
super(getActivity(),android.R.layout.simple_list_item_1,singlePost);
}
#Override
public View getView(int position, View convertView, ViewGroup parent){
if(convertView == null){
convertView = getActivity().getLayoutInflater().inflate(R.layout.fragment_post_feed_item,null);
}
SinglePost p = getItem(position);
TextView tvUserName = (TextView)convertView.findViewById(R.id.tvUN);
tvUserName.setText(p.getUserName());
TextView tvStatus = (TextView)convertView.findViewById(R.id.tvStatus);
tvStatus.setText(p.getStatus());
return convertView;
}
}
}
I have 2 other fragments but i'll post one as an example. Here is my adapter for the viewpager.
Adapter
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import com.mycompany.neighbors.Fragments.MapFragment;
import com.mycompany.neighbors.Fragments.NewsFeedFragment;
import com.mycompany.neighbors.Fragments.ProfileFragment;
/**
* Created by joshua on 5/25/2016.
*/
public class Adapter extends FragmentPagerAdapter {
private String Fragment[] = {"Posts" , "Map" , "Profile"};
public Adapter(FragmentManager fm){
super (fm);
}
#Override
public Fragment getItem(int position) {
switch(position){
case 0:
return new NewsFeedFragment();
case 1:
return new MapFragment();
case 2:
return new ProfileFragment();
default:
return null;
}
}
#Override
public int getCount(){return Fragment.length;}
#Override
public CharSequence getPageTitle(int position) {
return Fragment[position];
}
}

Please check below link, It has very good explanation for your problem:
http://tamsler.blogspot.in/2011/11/android-viewpager-and-fragments-part-ii.html
Or you can try below code snippet:
1.Where you add fragment in view pager or view pager adapter:
MyFragment myFragment = MyFragment.newInstance();
mPageReferenceMap.put(index, "Some Tag");
getSupportFragmentManager().beginTransaction().add(myFragment,"Some Tag").commit();
2.To get the tag for the currently visible page, you then call:
int index = mViewPager.getCurrentItem();
String tag = mPageReferenceMap.get(index);
3.and then get the fragment page:
Fragment myFragment = getSupportFragmentManager().findFragmentByTag(tag);